Subscriber signaling system



Oct. 20, 1953 R. o. GRAY ETAL SUBSCRIBER SIGNALING SYSTEM 2 Sheets-Sheetl Original Filed July 2. 1948 THE/R AGEN T Oct. 20, 1953 R. o. GRAYETAI. 2,656,408

SUBSCRIBER SIGNALING SYSTEM Original Filed July 2. 1948 2 Sheets-Sheet 23o asv TUNER a VIDEO m DETECTOR AMPLIFIER X sYNcH. VERT. SIGNAL swEEPsEPARAToR DRIVE ,55

a f3 /37 PuLsE HoRIz.

PHASE swEEP MoDuLAToR DRIVE OPERATOR a SWITCH '9 KEY FREQ. PHASE f4v,

wIre line conductor to 1ransmi1ter.

3 FILTE R FDR GDDING SIG. ./39 v AuDIo TUNER uw AND AMPLIFIER DETECTORRICHARD yO. GRAY' ERwIN M. R cHKE 1 ENToRs Patented Oct. 20, 1953SUBSCRIBER SIGNALING SYSTEM Richard 0. Gray and Erwin M. Roschke,Broadview, Ill., assignors to Zenith Radio Corporation, a corporation ofIllinois Original application July 2, 1948, Serial No. 36,778. Dividedand this application May 21,

1949, Serial No. 94,643

l 17 Claims.

I This invention relates to radio signalling systems, and moreparticularly to such systems of the subscriber type.

This application is a division of copending application Serial No.36,778, filed July 2, 1948, in the names of Richard O. Gray and Erwin M.Roschke, entitled Subscriber Signalling Systems and assigned to thepresent assignee,

It is an object of this invention to provide a subscription transmittingsystem in which a transmitted signal is coded by means of a codingsignal having a certain characteristic, and` in which the characteristicof the coding signal is altered from time to time.

It is a further object of this invention to provide such a systemwherein key signals are transmitted to subscriber receiver systems toindicate the times of occurrence of such changes in characteristics inthe above coding signal.

Yet another object of this invention is to provide such a system whereinsuch key signals are transmitted to subscriber receiver systems by meansof some private link, such as a telephone line, power line and the like,between transmitter and receiver.

A still further object of this invention is to provide such a system, inwhich the above mentioned coding signal is transmitted concomitantlywith the transmitted coded signals to be utilized in subscriberreceiving systems for decoding the coded signals.

' It is an additional object of this invention to provide a subscriptiontelevision transmitter wherein mode changes are effected at a ratefaster than the recurrence rate of the scanning fields.

A more particular object of this invention is to provide a televisionsystem in which a coding signal is utilized for coding a transmittedtelevision signal, and wherein the coding signal is transmitted tosubscriber receiver systems modulated preferably on the audio carrierportion of the television signal.

Yet another particular object of this invention is to provide means insuch a television system for changing the characteristics of the codingsignal from time to time, and for transmitting key signals to indicatethe times of occurrence of such changes, these key signals beingtransmitted to subscriber receiver systems by way of power lines, phonelines, or the like.

The features of this invention, which are believed to be new, are setforth with particularity in the appended claims. The invention itself,however, together with further objects and advantages thereof may bestbe understood by reference to the following description when taken inconjunction with the accompanying drawings, in which:

Figure l shows a television transmitter system incorporating theinvention, and

Figure 2 shows a receiver system operating in conjunction with thetransmitter of Figure l.

The various components that constitute the systems of Figure 1 andFigure 2 are in themselves either quite conventional, or have beenpreviously described in copending application Serial No. 742,374,entitled Radio Wire Signalling System, Ellett et al., led April 18,1947, and assigned to the present assignee and issued as Patent2,510,046 on May 30, 1950; or in cepending application Serial No.773,848, entitled Subscription Image Transmission System and Apparatus,Roschke, filed September 13, 1947,.also assigned to the present assigneeand issued as Patent 2,547,598 on April 3, 1951. These components aretherefore shown in block form, and a detailed description thereof isbelieved to be unnecessary'. y

Referring now to Figure 1, the television transmitter shown hereinincludes a usual camera I. Camera I comprises a conventional lens system2 for focusing images upon the screen of television pick-up tube 3,pick-up tube 3 being of the iconoscope or image orthicon type, andincluding a horizontal scanning coil 4 and vertical scanning coil 5.Video signals from tube 3 are amplified in video amplier stages 6, andsynchronizing signals and blanking pedestals are mixed with thesevideosignals in synchronizing signal and pedestal mixer stage 1. Signals fromstage 1 are impressed on background reinsertion device 8, and theresulting program signals, appropriately adjusted as to backgroundlevel, are modulated on the video carrier in carrier wave generator andmodulator stage 9, and thence radiated from antenna I0. Vertical andhorizontal synchronizing signals are generated in Vertical andhorizontal synchronizing signal generators I I, and these signals areapplied to stage 'I by way of leads I2 and I3 respectively. Verticalsynchronizing signals from stage II are further impressed on verticalsweep generator I4, the output of which is coupled to the verticalscanning coil 5 of tube 3. Similiarly, horizontal synchronizing signalsfrom stage II are further impressed on horizontal sweep generator I5through a conventional pulse phase modulator I6. Reference is madetopage 478 of Wave Forms, MIT Radiation Lab. series, volume 19,McGrawdescribed video signals are received on antenna 39, and suchsignals are tuned and detected in tuner and detector stage 40. A tunedand detected signal is amplified in audio amplifier 4I, and reproducedin signal translating device 42. The previously described coding signalis removed from the audio carrier by filter stage 43, and this codingsignal is impressed on pulse modulator 38 through phase inverter andswitch 44, this phase inverter and switch being similar to switch 2| ofFigure 1.

In the absence of key signals on conductors I9, phase inverter andswitch 44 passes the coding signal from filter 43 to modulator 3B in anoninverted manner, and the horizontal sweep of the receiver image tubeis changed to correct changes in the timing of the video signalcomponents relative to the horizontal synchronizing signal components ofthe received television signal, and tube 33 therefore reproduces thereceived video signal.

tor IB is inverted at the transmitter from time to time, such changesbeing indicated by the presence of key signals on conductors I9. Uponthe receipt of such key signals, key frequency filter and switchoperator 45, in response to the next succeeding vertical blanking pulseon leads 46 from vertical sweep drive 35, operates stage 44 to invertthe phase of the received coding signal as applied to modulator 38 incorrespondence to such inversion at the transmitter, so that tube 33continues to reproduce the received video signal.

While a particular embodiment of the invention has been shown anddescribed, modifications may be made without departing therefrom. Theappended claims are intended to cover any such modifications as fallWithin the true spirit and scope of the invention.

We claim:

l. A subscription transmitter system comprising: apparatus for producingelectrical signals representing intelligence to be transmitted by saidsystem; coding means coupled to said apparatus for coding saidelectrical signals in response to an applied coding signal; meanscoupled to said apparatus for transmitting said coded electrical signalsto a point remote from said transmitter; a first coding-signal sourcefor supplying a first coding signal to said coding means to code saidelectrical signals in accordance with a certain coding scheduledetermined by a characteristic of said first coding signal; a source ofa second coding signal different from said first coding signal;apparatus coupled to both of said coding signal sources and to saidcoding means for altering at least during spaced time intervals saidcharacteristic of said first coding signal thereby to vary said codingschedule in accordance with said second coding signal; means coupled tosaid first coding-signal source for transmitting a first key signal overone channel; and means coupled to said second codingsignal source fortransmitting a second key signal over another channel.

2. A subscription transmitter system comprising: apparatus for producingelectrical signals representing intelligence to be transmitted by saidsystem; coding means coupled to said apparatus for coding saidelectrical signals in response to an applied coding signal; meanscoupled to said apparatus for transmitting said coded electrical signalsto a point remote from said transmitter; a first coding-signal sourcefor supplying a first coding signal to said coding However, aspreviously stated the phase of the coding signal as applied tomodulameans to code said electrical signals in accordance with a certaincoding schedule determined by a characteristic of said first codingsignal; a source of a second coding signal different from said firstcoding signal; apparatus coupled to said second coding-signal source anddisposed. between said first coding signal source and said. coding meansfor alterning at least during spaced. time intervals said characteristicof said first; coding signal as applied to said coding means thereby tovary said coding schedule in accordance with said second coding signal;means coupled to said first coding-signal source for transmitting afirst key signal over one channel; and means coupled to said secondcoding-signal source for transmitting a second key signal over anotherchannel.

3. A subscription transmitter system comprising: apparatus for producingelectrical signals representing intelligence to b e transmitted by saidsystem; coding means coupled to said apparatus for coding saidelectrical signals in response to an applied coding signal; meanscoupled to said apparatus for transmitting said coded electrical signalsto a point remote from said transmitter; a first coding-signal sourcefor supplying a coding signal to said first coding means to code saidelectrical signals in accordance with a certain coding scheduledetermined by said first coding signal; a source of a second codingsignal different from said first codingr signal; apparatus coupled tosaid second codingsignal source and disposed between said firstcoding-signal source and `Said coding means for inverting during spacedtime intervals the phase of said first coding signal as applied to saidcoding means thereby to vary said coding schedule in accordance withsaid second coding signal; means coupled to said first coding-signalsource for transmitting a first key signal over one channel; and meanscoupled to said second coding-signal source for transmitting a secondkey signal over another channel.

4. A subscription transmitter system comprising: apparatus for producingelectrical signals representing intelligence to be transmitted by saidsystem; coding means coupled to said apparatus for coding saidelectrical signals in response to an applied coding signal; meanscoupled to said apparatus for transmitting said coded electrical signalsto a point remote from said transmitter; a first coding-signal sourcefor supplying a first coding signal to said coding means to code saidelectrical signals in yaccordance with a certain coding scheduledetermined by a characteristic of said rst coding signal; apparatusdisposed between said first codingsignal source and said coding meansand responsive to an applied signal for alterning said characteristic ofsaid first coding signal as applied to said coding means thereby to varysaid coding schedule; a key-signal source for supplying a key signal tosaid last-mentioned apparatus to effect said alteration in saidcharacteristic of said first coding signal during spaced time intervalsdetermined by said key signal; means coupled to said first coding-signalsource for transmitting a first decoding signal over one channel; andmeans coupled to said key-signal source for transmitting said key signalover another channel.

5. A subscription transmitter system comprising: apparatus for producingelectrical signals representing intelligence to be transmitted 'by'vsaid system; coding means coupled to said apbfi 'iiaiisiiiicii bylvs'ii'idsysiem; @ding means Gordan@ with ii certain 'dii'i'igSciieauieaiei'- c''u idy tf ii apparati@ for codingfat leas'tgne minedby a ehractiisii, if Said coding signal; d ghvals. ip S-IHSE lan alPRleqCoding mea-'ns for ppiyng said coding Signal to said means Coupled t0Said apparatusor audio-signai transmitting means for transmi# sion tosaid remote point comb'hd with Sad ,ng Signal Sr for. supplying a mstcoding audio signal; apparatus disposd btw sad s1 `al to said codingmeans'tio code said one slgou ce a u sam coding m ans and res l0. Asubscription television transmitter system comprising: apparatus forproducing a television signal representing image intelligence to betransmitted by said system; coding means coupled to said apparatus forcoding said television signal in response to an applied coding signal;means coupled to said apparatus for transmitting said coded televisionsignal to a point remote from said transmitter; apparatus for producingan audio signal representing sound intelligence to be transmitted bysaid system; means coupled to said audio signal producing apparatus fortransmitting said audio signal to said remote point; a coding-signalgenerator coupled to said coding means for producing a coding signal toeffect said coding of said television signal in accordance with acertain coding schedule determined by said coding signal; means forapplying said coding signal to said audio-signal transmitting means fortransmission to said remote point combined with said audio signal; aphase inverter disposed between said generator and said coding means andactuated by an applied signal for inverting the phase of said codingsignal as applied to said coding means thereby to vary said codingschedule; and a key-signal generator coupled to said phase inverter forproducing a key signal to actuate said inverter during spaced timeintervals. f l 11. A subscription television transmitter systemcomprising: a picture-converting device; a

scanning system for controlling said device to develop during recurrenttrace intervals a videofrequency signal representing a scanned subjectand including a synchronizing-signal generator for developing duringinterposed retrace intervals a synchronizing signal representing atiming characteristic of said device; means, including a mixer ampliercoupled to said converting device and to said scanning system fordeveloping a composite television signal including in alternationvideo-frequency components and synchronizing-signal components; codingmeans included in said scanning system for varying the time relationbetween said video-frequency and synchronizing-signai components inresponse to an applied coding signal; means coupled to said mixeramplifier for transmitting said television signal to a point remote fromsaid transmitter; a coding-signal generator for supplying to said codingmeans a coding signal to vary said time relation in accordance with apredetermined schedule determined by a characteristic of said codingsignal; apparatus disposed between said coding-signal generator and saidcoding means and actuated by an applied signal for altering saidcharacteristic of said coding signal as applied to said coding meansthereby to vary said schedule; and a key-signal generator controlled bysaid synchronizing-signal generator and coupled to said last mentionedapparatus for developing a key signal to actuate said last mentionedapparatus during spaced time intervals.

12. A subscription television transmitter system comprising: apicture-converting device; a scanning system for controlling said deviceto develop during recurrent trace intervals a videofrequency signalrepresenting a scanned subject and including a synchronizing-signalgenerator for developing during interposed retrace intervals asynchronizing signal representing a timing characteristic of saiddevice; means including a mixer ampliiler coupled to said convertingdevice and to said scanning system for developing a composite televisionsignal including in alternation video-frequency components andsynchronizingsignal components; coding means included in said scanningsystem for varying the time relation between said video-frequency andsynchronizingsignal components in response to an applied coding signal;means coupled to said mixer amplii'ler for transmitting said televisionsignal to a point remote from said transmitter; a codingsignal generatorfor supplying to said coding means a coding signal to vary said timerelation in accordance with a predetermined schedule determined by acharacteristic of said coding signal; apparatus disposed between saidcoding-signal generator and said coding means capable of being actuatedto alter said characteristic of said coding signal as applied to saidcoding means thereby to vary said schedule; a key-signal generatorcontrolled by said synchronizing-signal generator for developing a keysignal for transmission to said remote point over a private link; and anoperator circuit coupled to said lastmentioned apparatus and responsiveto the joint application of said synchronizing signal and said keysignal for actuating said last-mentioned apparatus during spaced timeintervals.

13. A subscription television transmitter system comprising: a.picture-converting device; a. scanning system for controlling saiddevice to develop duringrecurrent trace intervals a videofrequencysignal representing a scanned subject and including asynchronizing-signal generator for developing during interposed retraceintervals a synchronizing signal representing a timing characteristic ofsaid device; means including a mixer amplifier coupled to saidconverting device and to said scanning system for developing a compositetelevision signal including in alternation video-frequency componentsand synchronizing-signal components; a coding circuit included in saidscanning system for varying the time relation between saidvideo-frequency and synchronizing-signal components in response to anapplied coding signal; means coupled to said mixer amplifier fortransmitting said television signal to a point remote from saidtransmitter; apparatus for producing an audio signal representing soundintelligence to .be transmitted by said transmitter; means coupled tosaid audio signal producing apparatus for transmitting said audio signalto said remote point; a coding signal generator coupled to said codingcircuit for developing a coding signal to effect said variation in saidtime relation in accordance kwith a predetermined schedule determined bysaid coding signal; means for applying said coding signal to saidaudio-signal transmitting means for transmission to said remote pointcombined with said audio signal; a phase inverter disposed between saidcoding-signal generator and said coding circuit and actuated by anapplied signal for inverting the phase of said coding signal as appliedto said coding circuit thereby effecting a variation in said codingschedule; and a key-signal generator controlled by saidsynchronizing-signal generator and coupled to said phase inverter fordeveloping a key signal to actuate said inverter during spacedintervals; and means for transmitting said key signal to said remotepoint.

14. A subscription television system comprising a transmitter and areceiver; said transmitter including, apparatus for producing atelevision signal representing image intelligence to be transmitted tosaid receiver, coding means coupled to said apparatus for coding saidtelevision signal in response to an applied coding signal, means coupledto said apparatus for transmitting said coded television signal to saidreceiver, apparatus for producing an audio signal 4repi"'esenting"Soundinl telligence to betrar'isniitted to said receiver, m'a'ns coupled tosaid audio signal producingv paatus for transmitting said audio signal'tosaid o' receiver, a coding-signal "source coupled to said coding meansfor producing a coding 'signal-to effect saidcoding of said televisions'ignai'n acl cdan'ce with a certain coding schedule deterfri-ined by acharacteristic of saidv coding signal, means forapplyingl'said codingsignal'tov said audio-'signal transmitting :means for transmission to"s'alid recverfcornbind virvith said audio signal, apparatusdisposdBetween said source andsaid coding m'easandire'sponsive to zin-:appliedsignal foi? alteringSadtchaacteristic of Said ycoding sig'` na'flasapplied tof'said coding neans thereby to vary said "uingi s" jdul akey-signers@ coiipled'td' said'last'nentioned apparatus" for p 1' din'g'keyfsignai'fto 'effect ssi-1d 'alteration 1p said' charateristm'ofsaidpdmgf'sifgii duljng' spaced'tirne"ntervals,`- and alirie'circuit cpled-v tojsaiakeyLsignaisour receiver f o'r supplyiigfsaid ky signalvto" a ceiver and' said`r` -re'cever including? triage;- reprodung dvicearida" sound-re'p'rc du:c:i1f`1g'de` vc; tel'fv'isviori"Iappar'atus'for"supplyingsaid tel-e- Visioh"'fsignaI'to-f s'ai'dimVlrpr'o' Vi" e, audioapparatu's"for-supply1 g aid'a dio s1gn ig alfora-1119er? gnalas pn correspondence ingf saiurehafacteristic ofsa'idd1 puedel said-, deco-amg 'inea with .the alterationsbfi-'said':characteristic-at saidjf mode of transmissio ffsidtmiio si 30s ystein for supplying a means coupled to said second coding-signalsourcefoitrsmttingafs 1 @Yer einem@ Channel# 16. Asubscriptiontelevision transmitter com feren'tco'ding sch dul ap'par'atusources to *recei'i/y signals and to'produ coding` signal'repr'esenting'fective1yto codesaidtelevisionsign 1' a o coding nreans'eie means at' r.te 'f` recurrence rate of sai coupled to said` cont ete-nt Number *ACountry l Date 3.3 8 i 9 Great-Britain J-an. "26;- 1933

